i picked up one of these modded s7s from sidehack..
with the stock fans i was having trouble keeping it running at night.. even lowering the fans to 20% was not enough to keep the boards warm enough.. once they got to 40c or so they will shut off.
we are having pretty good weather here, but it still cools off at night.. upper 50s at night and 80s during the day.
i put on a pair of AFB1212-SHE fans i got for my s5s.
https://www.amazon.com/Delta-Electronics-AFB1212SHE-120x120x38mm-connector/dp/B004Y1HLA8these fans do have a bit more of a whine to them than the stock fans.. but the air flow is slower and the s7 doesnt whistle, over all i think they are more quiet. like a s5.
running them at AUTO they seem to be running pretty good at 600 speed. right at 4000 ghs and using 1023 at the wall. my unmodded s7 at 600 speed uses 1280 watts.
they speed up to about 3400 rpm during the day and slow down to around 3100 at night. they max out at 3600 so there is still room for when it gets hotter.
the temps are holding right at 55-64c.
i think you can flash the 1-fan rom on it and just use one stock fan.. not sure tho.. i didnt try. i might try it on my other s7 when i get the pickit3 i ordered from china.
overall the mod is well worth it.. you dont lose much speed (actually i was running my s7 at 600 already) and you lose almost 300 watts. you do have to do something with the fans tho, the boards need to be above 50c to stay stable.